Numerous types of material heating, melting and dispensing units exist for a variety of industrial applications. One type of device includes an arrangement in which a heated platen is lowered into the open end of a container for melting and/or liquifying material contained therein and pumping the material, for example, to various types of dispensing devices. The platens generally have an engagement surface which may either be generally smooth or may have a plurality of projecting heat exchanging elements, such as fins. A platen having a smooth heated surface leaves less residue in the bottom of the container and is typically easier to clean than a finned platen. However, smooth platens generally have lower output capabilities than a finned platen. Therefore, smooth platens may not be suitable for use with dispensers demanding a high flow rate of material from the platen. In these instances, the projecting heat exchanging elements or fins on a platen can provide a higher melt rate and therefore higher output from the platen. Also, due to the increased contact with the heated surfaces of the fins, higher temperatures are possible.
Another problematic area in this technology relates to the downtime experienced when changing over from a depleted container of material to a new container of material. Often, a production process stops during this changeover time and this effectively results in higher production costs. One solution to this problem involves using a two unit system in which a second drum unloader takes over while the first unit is reloaded with a new container of material. This is an undesirable solution in many cases due to the increased cost of the two unit system.
Finally, many platens heat the material sufficiently to allow it to be pumped, however, the material may not be heated close to a desired application temperature. For this reason, downstream hoses, manifolds and other components must supply additional heating energy to the material.
While current and past finned platens have served certain needs in regard to increasing melt temperature and/or increasing flow rate, improvements are constantly desired in the industry. Increasing the flow rate even further and/or increasing the temperature of the liquified thermoplastic material is a continuing need. There are increasing numbers of industrial applications requiring greater output from a drum unloader. Increasing the output from a drum unloader can decrease overall production time and may enable the supply of additional downstream dispensing devices with the proper amount of pressurized liquid material. Finally, increasing the heating capacity of a platen can reduce the need for additional heat energy requirements between the platen and the ultimate dispensing devices.
For reasons such as those described above, it would be desirable to provide apparatus including a platen for heating, melting and dispensing various materials such as solid thermoplastic or rubber materials with higher liquid output and/or temperature.